ABSTRACT
Chromosomes were observed by Nageli in 1842, soon after the discovery of the nucleus under the microscope, as objects that appeared at cell division. The fact that chromosomes were transferred to the two new daughter cells convinced researchers that they constituted the materials carrying the information of inheritance. From a morphological point of view, chromosomes can be divided into the two phases of the cell cycle; i.e., the metabolic stage observed as a nucleus in the cell and the dividing stage at which time the characteristic morphology of the chromosomes of the species or individual appear. The dividing stage consists of mitosis and meiosis. Metaphase chromosomes are most usually studied after the inclusion of a pretreatment to accumulate the condensed chromosomes. Prometaphase chromosomes, especially the small plant chromosomes that condense to small dots or rods at the metaphase stage, have been known to contain critical information.
